In an electronic image forming apparatus such as a printer or copy machine, a developer is supplied by a developing device to an electrostatic latent image on a photoconductive drum and a developer image is generated.
This developing device includes a developing roller which supplies the developer to the photoconductive drum, and a mixer which stirs a carrier and a toner and supplies the developing roller with the developer acquired by this stirring.
The developing roller has plural magnets within a rotating outer roller. The developing roller catches the developer using catching pole, which is one of the plural magnets, then supplies the developer to the photoconductive drum using another magnet, and separates the used developer from the outer roller using another magnet.
In the related art, the used developer that is separated may adhere to the catching pole. The used developer that is separated has low toner content. Therefore, supplying the used developer to the photoconductive drum may deteriorate image quality.
In view of this point, a technique of providing a control plate to prevent the collected used developer from being drawn to the catching pole of the developing roller is proposed.
However, this technique requires high accuracy in the spacing between the developing roller and the control plate and therefore needs a number of processes for assembly and an increased number of components.
Thus, there is demand for a developing device, an image forming apparatus and an image forming method such that adherence of the used developer separated from the developing roller to the catching pole can be prevented efficiently.